And Thomas answered and said unto him, My Lord (ὁ κύριός μου) and my God. (John 20:28)
Commenting on the use of "my Lord," Edwin Abbot wrote:
What then is the meaning? "Lord" certainly cannot mean "Jehovah." "My Jehovah" would be an unheard of monstrosity. But "my Lord" might mean "my dear Lord," or "my dear Master" as the term is used by Mary Magdalene. And it would be appropriate that this almost unique appellation should be used by Thomas as by Mary, in connexion with a manifestation of the risen Saviour. If it is so used here, is "my Master" subject or predicate? If it were predicate we should have to supply "Thou art," or "It is," which is inserted in xxi. 7 "it is the Lord (ο κυριους εστιν)." But could εστιν have been omitted there? In any case it could hardly be omitted here, since the meaning required would be "it is indeed my Lord," so that it would be emphatic. But if we take it "My [dear] Lord" as subject, we may readily imagine a pause after it, while the speaker is overwhelmed with amazement and joy, is attempting to express his feeling about the Lord. He might have added "has indeed risen from the dead" or "has been indeed restored to me," but he means a great deal more than that. When he has uttered "my Lord," he feels that "there is none in heaven" whom he could "desire in comparison" with this "Lord." In effect, his Lord has become to him one with his God, so that he may say "My Lord is also my God." (Edwin A. Abbott, Johannine Grammar [London: Adam and Charles Black, 1906], § 2050 p. 94)